INTRODUCTION 71 



seems not far to seek that they represent the last remnants of an ancient African 

 fauna. This hjq^othetical (p. 479) primitive fauna was clearly analogous to that 

 of South America, and it seems probable that there existed a means of communica- 

 tion between the two continents either by way of Antarctica or a trans-Atlantic 

 landmass. It is possible that both had received their fauna from the north in pre- 

 tertiary times. Certain it is, however, that both were later connected with the 

 northern continents, communication in the eastern hemisphere being established 

 much earlier than in the western, probably before the Miocene. Africa is now 

 inhabited by mammalian types of various orders, which have become differentiated 

 into genera and even families, and which are practically unknown among the fossil 

 as well as the living fauna of Europe and Asia. When we consider how large a 

 space of time is required for the development of even slight modifications, the con- 

 clusion seems forced wpon us that a large proportion of the present faunal types of 

 Africa existed there throughout the Tertiary. The antelopes (p. 480), then as now, 

 seem to have had their chief centre of evolution in Africa, and perhaps the giraffes 

 likewise. Whether the horses, rhinoceroses and even the enigmatical proboscideans 

 were native to the same continent in earl_y Tertiary times, must remain an open 

 question. It is very probable (p. 488) that the Pikermi fauna [a rich Upper Miocene 

 fauna of Greece, see map, p. 267], save for the forms that can be referred back 

 to the European middle Miocene, is derived from Africa. The way into Asia seems 

 to have been less open at this time, no African forms having been found east of 

 Maragha (Persia). In the Pliocene, on the other hand, communication with Asia 

 seems to have been more intimate than with Europe. It is a remarkable fact 

 (p. 488) that Chceropsis (the pigmy hippopotamus), and Phacochmrus (the wart- 

 hog) at no time migrated out of Africa. Perhaps Ethiopia was better able to 

 maintain its inhabitants uninterruptedly than any part of Asia or Europe because 

 it remained for the most part unaffected by the great marine and orogenic move- 

 ments, and b}^ the great lowering of temperature at the close of the Tertiary." 



In 1899-1900 Osborn developed and published his "Theory of Successive 

 Invasions of an African Fauna into Europe." He observes (p. 56) : 



"Let us therefore clearly set forth the hypothesis of the Ethiopian region or 

 South Africa as a great center of independent evolution and as the source of succes- 

 sive northward migrations of animals, some of which ultimately reached even the 

 extremity of South America — I refer to the Mastodons. . . . 



"T\\G first of these migrations we may suppose brought in certain highly special- 

 ized ruminants of the Upper Eocene, the anomalures or peculiar flying rodents of 

 Africa; with this invasion may have come the pangolins [Pholidota] and aardvarks 

 [Tubulidentata], and possibly certain armadillos, Dasypodida;, if M. Filhol's iden- 

 tification of Necrodasypus is correct. A second invasion of great distinctness may 

 be that which marks the beginning of the Miocene when the mastodons and dino- 

 theres first appear in Europe, also the earliest of the antelopes. A third invasion 

 may be represented in the base of the Pliocene by the increasing number of antelopes, 

 the great giraffes of the ^Egean plateau, and in the upper Pliocene hy the hippo- 

 potami. With these forms came the rhinoceroses with no incisor or cutting teeth, 

 similar to the smaller African rhinoceros, D. hicornis. Another recently discovered 

 African immigrant upon the Island of Samos in the iEgean plateau is Pliohyrax 



